package com.knight.server.netty.registry;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.*;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
import io.netty.handler.codec.LengthFieldPrepender;
import io.netty.handler.codec.serialization.ClassResolvers;
import io.netty.handler.codec.serialization.ObjectDecoder;
import io.netty.handler.codec.serialization.ObjectEncoder;

public class RpcRegistry {
    private int port;

    public RpcRegistry(int port) {
        this.port = port;
    }

    public void start() {
        EventLoopGroup bossGroup = new NioEventLoopGroup();
        EventLoopGroup workerGroup = new NioEventLoopGroup();

        ServerBootstrap bootstrap = new ServerBootstrap();
        bootstrap.group(bossGroup, workerGroup)
                .channel(NioServerSocketChannel.class)
                .childHandler(new ChannelInitializer<SocketChannel>() {

                    @Override
                    protected void initChannel(SocketChannel ch) throws Exception {

                        ChannelPipeline pipeline = ch.pipeline();
                        /**
                         * maxFrameLength：框架的最大长度。如果帧的长度大于此值，则将抛出 TooLongFrameException。
                         * lengthFieldOffset：长度字段的偏移量：即对应的长度字段在整个消息数据中得位置
                         * lengthFieldLength：长度字段的长度。如：长度字段是 int 型表示，那么这个值就是 4（long 型就是 8）
                         * lengthAdjustment：要添加到长度字段值的补偿值
                         * initialBytesToStrip：从解码帧中去除的第一个字节数
                         */
                        pipeline.addLast(new LengthFieldBasedFrameDecoder(Integer.MAX_VALUE, 0, 4, 0, 4));
                        //自定义协议编码器
                        pipeline.addLast(new LengthFieldPrepender(4));
                        //对象参数类型编码器
                        pipeline.addLast("encoder", new ObjectEncoder());
                        pipeline.addLast("decoder", new ObjectDecoder(Integer.MAX_VALUE,
                                ClassResolvers.cacheDisabled(null)));
                        pipeline.addLast(new RegistryHandler());

                    }
                }).option(ChannelOption.SO_BACKLOG, 128)
                .childOption(ChannelOption.SO_KEEPALIVE, true);

        try {
            ChannelFuture future = bootstrap.bind(port).sync();
            System.out.println("RPC Server start listen at "+port);
            future.channel().closeFuture().sync();
        } catch (InterruptedException e) {
            e.printStackTrace();
            bossGroup.shutdownGracefully();
            workerGroup.shutdownGracefully();
        }

    }

    public static void main(String[] args) {
        new RpcRegistry(8080).start();
    }
}
